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@PHDTHESIS{Robrecht:894915,
      author       = {Robrecht, Sabine},
      title        = {{P}otential depletion of ozone in the mid-latitude
                      lowermost stratosphere in summer under geoengineering
                      conditions},
      volume       = {545},
      school       = {Universität Wuppertal},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2021-03477},
      isbn         = {978-3-95806-563-5},
      series       = {Schriften des Forschungszentrums Jülich. Reihe Energie
                      $\&$ Umwelt / Energy $\&$ Environment},
      pages        = {185 S.},
      year         = {2021},
      note         = {Universität Wuppertal, Diss., 2020},
      abstract     = {The world's climate is changing, largely because of
                      anthropogenic emissions of greenhouse gases (GHG).
                      Increasing atmospheric GHG concentrations result in global
                      warming, which changes habitats all around the globe. For
                      limiting the risks of global warming, a supporting option
                      could be the application of sulfate geoengineering. The
                      concept of sulfate geoengineering is to inject sulfate
                      aerosols into the stratosphere extenuating the sunlight,
                      which reaches and thus warms the surface of the Earth. In
                      this way, the surface temperature could possibly be kept at
                      today's level avoiding negative consequences of GHG induced
                      global warming. However, sulfate geoengineering is not free
                      of risks and these potential risks have to be explored
                      before the application of geoengineering can be considered.
                      This thesis is aimed at assessing the risk of ozone loss
                      known from polar winter to occur in the mid-latitude
                      lowermost stratosphere in summer as a potential side effect
                      of sulfate geoengineering. These ozone loss processes were
                      further proposed to potentially occur in the mid-latitudes
                      for today's conditions in combination with convective
                      overshooting events transporting water vapour into the dry
                      stratosphere. If these ozone loss processes occur, the
                      UV-exposure in the densely populated mid-latitude northern
                      hemisphere would increase in summer. In this thesis, the
                      chemical ozone loss mechanism in the mid-latitudes and its
                      sensitivity to a variety of conditions is extensively
                      analysed by conducting box-model simulations with the
                      Chemical Lagrangian Model of the Stratosphere (CLaMS). This
                      analysis shows that a threshold in water vapour has to be
                      exceeded for stratospheric ozone loss to occur. This water
                      vapour threshold is mainly determined by the temperature and
                      sulfate content of the air mass. The extent of ozone loss
                      depends on available chlorine and bromine concentrations and
                      the duration of the time period over which chlorine
                      activation can be maintained. However, a simulation for
                      conditions over North America, which are realistic but
                      selected to be mostsuitable for this ozone loss process, did
                      not show signicant chlorine activation. Moreover, the
                      likelihood for this ozone loss process to occur today or in
                      future scenarios is determined considering both climate
                      change and an additional application of sulfate
                      geoengineering. Therefore, atmospheric conditions causing
                      chlorine activation are determined based on CLaMS box-model
                      simulations and compared with conditions found in the
                      lowermost stratosphere inresults of climate simulations
                      using the Geoengineering Large Ensemble Simulations (GLENS).
                      Extensive sensitivity studies in this thesis show a 2-3
                      times higher likelihood for chlorine activation in the
                      future scenario with sulfate geoengineering than for today.
                      However, even if geoengineering were applied, the likelihood
                      for chlorine activation to occur above North America remains
                      low (max. $\thicksim$3.3\%), destroying less than 0.4\% of
                      ozone in the lowermost stratosphere. An upper limit for
                      total ozone column reduction of 0.11 DU (less than 0.1\% of
                      column ozone) is deduced in this thesis. Overall, this
                      thesis demonstrates a negligible risk for chlorine catalysed
                      ozone loss to occur in the lowermost stratosphere over North
                      America in summer for conditions today and in future, even
                      if sulfate geoengineering were applied. This is an important
                      contribution to assessing the risks of a potential
                      application of sulfate geoengineering in future.},
      cin          = {IEK-7},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {899 - ohne Topic (POF4-899)},
      pid          = {G:(DE-HGF)POF4-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2021093005},
      url          = {https://juser.fz-juelich.de/record/894915},
}